Multiclavula caput-serpentis Lotz-Winter & Reschke, 2021

Reschke, Kai, Lotz-Winter, Hermine, Fischer, Christian W., Hofmann, Tina A. & Piepenbring, Meike, 2021, New and interesting species of Agaricomycetes from Panama, Phytotaxa 529 (1), pp. 1-26 : 8-10

Multiclavula caput-serpentis Lotz-Winter & Reschke , sp. nov. Figs. 7–9

Mycobank MB838255

Diagnosis: —Differs from other species in the genus by the combination of growth on soil, white to orange white, dorsiventrally organized basidiocarps with smooth stipe, 4−8-spored basidia and oblong to allantoid basidiospores.

Etymology: —caput (Latin) = head, serpens (Latin) = snake; referring to the shape of the basidiocarps.

Type: — PANAMA. Chiriquí Province: Sendero Los Quetzales , between Cerro Punta and Bajo Boquete, N 08°50’47.7’’ W 82°32’07.8’’, 2350 m a.s.l., upper montane cloud forest, on soil, 01 July 2018, K. Reschke, T. Hofmann (KaiR699) (holotype UCH9257 , isotype M-0312083) !

Description: —Thallus terricolous, covering an area of about 1.5 m ², thin, but visible as a green layer. Basidiocarps clavarioid, 5.0−7.0 mm high, emerging from the thallus, gregarious, scattered, predominantly separate, rarely two basidiocarps combined, entire, incised to fringed at the apex, or forked with 2–3 branches starting from half of the height, solid, delicate but waxy-tough to cartilaginous. Fertile part 2.0−5.5 × 0.3−0.5 mm, dorsiventrally applanate with a concave outline, with a tendency to furl along the length-axis when dry, with acute, straight or hooked, rarely obtuse apices, white to orange white (5A1−2). Stipe 0.5−1.5 × 0.3−0.7 mm, cylindrical to somewhat flattened, smooth, whitish. Dorsal side of the fertile part sterile, hymenium on ventral side of the fertile part and partly on apices, sometimes on both sides of the apex.

Basidiospores 6.0−7.3−8.5 × 2.0−3.7−3.5 µm, Q = 2.10−2.79−3.35 (n = 50), oblong to slightly allantoid, often somewhat centrally constricted, hyaline, smooth, thin-walled, inamyloid, with oil drop, frequently forming aggregates of 4−8 spores. Basidia 25−35 × 5.0−7.0 µm, initially ovoid to clavate, suburniform at maturity, thin-walled, hyaline, 4−8-spored, with up to 6.0 µm long sterigmata, clamped, easily collapsing after spore-shedding. Hyphal system monomitic. Hyphae generally thin-walled, septate, with clamp connections. Subhymenium composed of densely arranged, branched and intertwining hyphae. Trama hyphae parallel, sparsely branched, tightly packed and rarely intertwining, composed of cylindrical cells, approx. 50 × 1.0−2.0 µm. Some hyphae with refractive content present. Thallus consisting of a network of fungal hyphae, wrapping green algae, thus forming bulbils with a close contact of myco- and photobiont. Algal cells 8.0–9.0 × 6.0−7.0 µm, broadly ellipsoid, each surrounded by fungal hyphae of 1.0−2.0 µm diameter. Algae frequently forming ellipsoid autospores, 4.0−6.0 × 3.0−5.0 µm. Hyphae between bulbils narrow, about 1.0 µm wide.

Habitat: — Terricolous on loamy, stony soil, on a moist steep enbankment along a mountain path in montane cloud forest at 2350 m a.s.l. on the north slopes of Volcán Barú in Chiriquí, Panama .

Notes: —In the phylogeny (Fig. 8), Multiclavula caput-serpentis forms a clade with M. ichthyiformis Nelsen et al. in Nelsen et al. (2007: 1290), which also has dorsiventral basidiocarps. Multiclavula ichthyiformis , however, differs from M. caput-serpentis by basidiocarps with a strigose stipe and a thin, translucent fertile part, as well as by globose basidiospores and a p-distance of 12% in the ITS sequence data. Multiclavula hastula ( Corner 1950: 370) Petersen (1967: 214) , described from Malaysia, is similar to M. caput-serpentis by small, pale flesh coloured basidiocarps of similar shape. It was, however, described and illustrated by Corner (1950) as associated with cyanobacteria and having thin, soft flesh, hyphae with ampulliform swellings, and 4- to 6-spored basidia. The basidiospores of M. hastula are ellipsoid to narrowly ovoid and 5.0–7.0 × 2.0–3.0 µm in size ( Petersen 1967), while those of M. caput-serpentis are oblong to slightly allantoid and longer, 6.0−8.5 × 2.0−3.5 µm. The holotype of M. hastula has been studied by Corner (1950) and Petersen (1967), it is stored in formaline and thus not suitable for molecular analysis. Further collections of M. hastula have not been reported, but are necessary to reveal its phylogenetic affinities. Multiclavula petricola Masumoto & Degawa (2020: 157) , described from Japan, differs from M. caput-serpentis by its occurrence on stone, somewhat longer basidiospores and a more pronounced globular thallus. A dorsiventral organisation of its basidiocarps was not reported ( Masumoto & Degawa 2020). A further specimen of Multiclavula (PAN625), with affinity to M. mucida ( Persoon 1797: 55: Fr.) R.H. Petersen (Fig. 8), was collected in Panama. However, the material of this putatively further new species is insufficient for description.